Scientists and medical professionals, for example, have analyzed objects using 3-D imaging for some time. But now various methods have been developed to produce 3-D images, such as television images, for example, for general consumer applications. Among these methods, there is a basic distinction between sequential image transmission, in which the images for the right eye and the left eye are saved to a storage medium, or transmitted alternately, one after the other, and parallel transmission, in which the images are transmitted on two separate channels.
One disadvantage of transmitting sequential images for displaying 3-D images in conventional television systems is that this reduces the refresh rate for each eye to 25 images per second, which creates an unpleasant flickering for the viewer. When transmitting the sequential images in parallel, on separate channels for the left and right eyes, the refresh rate is not reduced and thus flickering does not occur. Problems may still arise with synchronizing both channels, however. Problems also may arise due to the requirements of the receiver, which must be able to receive and process two separate channels simultaneously. This is not possible for most television systems that are now generally available to consumers.
In future television systems, signal transmission and processing will likely be entirely digital. In a digital system, every image is broken down into individual pixels which are transmitted in digitized format. In order to reduce the bandwidth required for this process, the appropriate compression methods are used; however, these create problems for stereo transmission. For example, using block coding methods with a reasonable rate of compression, it is impossible to precisely reconstruct every individual line of an image. In addition, using interframe coding techniques, such as MPEG-2, it is impossible to transmit or save stereo images in a sequential image format because image information from one image is contained in another image. This creates what is called the “crosstalk effect,” which makes it impossible to clearly separate the right image from the left image.
Other methods with which a three-dimensional image sequence is generated based on a two-dimensional image sequence have been published in DE 35 30 610 and EP 0 665 697. An autostereoscopic system with interpolation of images is described in EP 0 520 179, and problems with detecting areas of motion in image sequences are discussed in “Huang: Image Sequence Analysis” (Springer Publishing House).
U.S. Pat. No. 6,108,005 describes a method for generating synthetic stereo images in which at least two images are generated based on a loaded image. At least one of the generated images is adjusted (enlarged, reduced, rotated, displaced, or changed) relative to the loaded image in such a way that at least parts of the image are displaced relative to other parts of the image in comparison to corresponding parts in another image. This method has the disadvantage that it is largely dependent on the skill of the operator to select the proper adjustments to generate a correct or natural stereoscopic appearance for the viewer.